It does not surpise me that a bounce would happen and fade quickly.  This applies to both parties.

THE NON-BOUNCE BOUNCE
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Ben Wikler  09.08.2004  

The sturdy, reliable Gallup Poll has released some numbers--and it turns out that the Bush bounce was a MYTH.

Ruy Texiera writes:
I think those of us who have expressed skepticism about the results of the Time and Newsweek polls can consider ourselves vindicated. The new Gallup poll, conducted entirely after the GOP convention and therefore the FIRST poll that TRULY measures Bush's bounce, shows Bush with a very modest bounce indeed: 2 points, whether you look at RVs or LVs. His support among RVs has risen from 47 percent before to 49 percent after the convention, so that he now leads Kerry by a single point (49-48) rather than trailing by a point.

What's more,

Note also that Bush's 2 point bounce from his convention (which, remember, is defined as the change in a candidate's level of support, not in margin) is the WORST EVER received by an incumbent president, regardless of party, and the WORST EVER received by a Republican candidate, whether incumbent or not (see this Gallup analysis for all the relevant historical data). In 2000, Bush received an 8 point bounce. And even his hapless father received a 5 point bounce in 1992.

And not only that!

Prior to the Republican convention, Kerry had a one point lead among RVs [Registered Voters] (47-46) in the battleground states. After the Republican convention, now that battleground voters have had a chance to take a closer look at what Bush and his party really stand for, Kerry leads by 5 in these same states (50-45)! Note that Kerry gained three points among battleground voters, while Bush actually got a negative one point bounce.

So, it turns out that we weren't the only ones who found the GOP convention nauseating.

Bush Gets Small Convention Bounce
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by Jeffrey M. Jones   September 06, 2004

The CNN/USA Today/Gallup post-Republican convention poll -- the first national poll conducted entirely after the completion of that convention -- shows George W. Bush has received a small increase in voter support. Bush’s share of the vote among likely voters increased by two percentage points, from 50% to 52%, while Democratic presidential candidate John Kerry’s share dropped by an equal amount, in the two-way race. Bush now leads Kerry by 52% to 45% among likely voters, compared with a 50% to 47% lead for Bush prior to the convention. Bush received an identical two-point bounce among registered voters, though the two candidates remain essentially TIED among this group.

http://www.gallup.com/poll/content/login.aspx?ci=12922