How long were you allowed to stay on 7.5mg (for insurance reasons)?

I have been on 7.5mg for almost 16 weeks now. (After 1 month each on 2.5 and 5mg). I feel like this dose is working well - I'm still losing, but getting closer to goal, so losing slower- which I am fine with. Today I got a call from the pharmacy stating that my insurance is asking for a PA in order to cover my meds this time - just wondering if this is "normal" and if perhaps they're trying to get me to go up to 10mg by doing this? I am trying to avoid going up unnecessarily I appreciate any insight/experience with this issue people have. I really dont want to have to stop taking this - I am down 45lbs so far and have very few side effects from the medication at this point, so dont want to go up "just because".