I think, and you said as much, that it's a little early to worry too much about a refusal. Especially considering you're doing multiple prey items it doesn't surprise me that she's starting to give you a little trouble. Just be patient with her, it's winter time and typically my snakes slow down eating this time of year as well. As far as the time it's taking her to strike, have you guys tried just drop feeding? Sometimes my BP does better when I just lay a feeder on top of his hide and let him get it when he's ready. It's also possible that because of the time it's taking her to strike that the feeder is just cooling off enough that she's losing interest in it.