Swaddling

My almost 3 month old gets swaddled everynight in the Halo sleepsack. 3 nights ago I found her almost on her stomach face down while swaddled and arms in. Luckily she was fine and content, so I placed her back on her back. She did it another time so my husband and I decided it was time to start transitioning. She used to sleep 6-8 hours wake up for a quick fed, than sleep another 2-4 hours. Now that we are allowing one arm out she isn't sleeping as well and waking up frequently. any suggestions ? I also read growth spurts are common by 3 months of age.