What is going on around her while you try to feed her? My LO did exactly the same thing one nice day when I decided to take her to the park for the first time. She was hungry, and let me know it, but every time I stuck the bottle in her mouth she spit it out because that tree blowing in the wind was WAY more interesting. She actually skipped a meal that day, at 2 oz (over 2 hour period) instead of 6. The new surroundings could have everything to do with it.
So long as your LO is a healthy weight, try not to worry. I find myself stressing about similar things too but try to remember that she's not 6 weeks anymore, she's 6 months. Sleeping longer or shorter than normal, eating more or less, it all evens out in the end. Like today for instance, it took me an hour to get her to nap, by that time it was time to eat. I let her go 5 hours inbetween eating because she was napping late. She's no worse for the wear. Only problem is she's going to have a late night tonight if she gets her last bottle in.
Good luck!!
Jill