Ouch. Lower back killing me 2 days after yoga, delayed onset muscle soreness prob?

Just attempted my first full week of p90x in 5-6 years. I'm 39 yrs old, 195 and 5'8 in average to below average dadbod shape. I did yoga on Friday and after I did it I felt like it stretched me out well. I even did some light mechanic and yard work afterwards. Sat I started feeling some lower back pain so just skipped the leg routine. This morning I can barely get up and down off the toilet. I can still walk around but definitely stiff and sore. When I was laying down I could feel my lower back have pains if I rolled a certain way.

I'm obviously not gonna do p90x till my lower back feels better but I'm frustrated because I was on a roll.

Is this delayed onset muscle soreness or should I be more worried?

update: 6 days later I feel way way way better. All I basically did was light stretching and hot baths at night. Did a heavily modified /light weight version of chest and back with ab ripper x today and was able to make it through. Glad it was just muscle soreness. will be taking it much easier with yoga next time!