Something came up at her incall. Perhaps she dropped a glass on the carpet and does not want you to get cut. Anything normal could have happened. Don't be alarmed unless you have not done your research on her.

to give the address at the time the appointment is made instead of using a two call system.

I believe they are comfortable doing that because -
1. That is what a therapeutic-only massage provider would also do.
2. They have a substantial amount of time with you on the table to assess whether or not they feel comfortable enough with you to put a smile on your face.

She may have out of town guests at home (if she works from home)...  Holiday season...  N Big Deal
Has she given you a Room Number or just the name of a hotel...  you'll still have to call to get the room.

gave you the room # in advance, run, don't walk, away.

That depends...

Weather the provider's original location was a solid place or just a tent that she can easily fold up and move 5 blocks north...or south... In the business the tent is usualy a hotel room...