Congratulations on your PU/PD success & the start of self soothing & longer naps.
Honestly, some days you just get short naps, sometimes there's no clear reason and it can just be a one off. I'd carry on as you were for a few more days, see if longer naps return. If not comeback, post your day in EASY format and we can chat it through.
How long you continue PU/PD is up to you. Personally though if my LO hadn't resettled after 20-30 mins max, I usually gave up as I couldn't face hours and hours in a darkened room with a baby who was grumpy because she wanted to get up and play!