This could indeed be her first egg coming off molt. You are doing well by keeping a close watch on her. Let her behavior guide you. If she's passed the obstruction, and it could have been hidden in that poop, she will very quickly return to normal behavior.
If she continues to have obstructing material inside her, she will be obviously uncomfortable, hunched, puffed up, lethargic, etc. Also, a steady watery discharge often accompanies an obstruction in the reproductive tract since it blocks the cecum where cecal poop is produced. It's also where excess fluids are distributed into the hen's body tissues. When blocked, the cecum discharges the watery fluid instead, resulting in the steady drip from the vent. It also risks the hen getting dehydrated, so water must be made always available as this makes a hen very thirsty.
I've learned all this the hard way. Every year at this time, my elderly SLW hen Lilith who is nearly twelve now, tries to lay a few eggs. Every damned year. Last year, after laying a perfect egg, she then had a blocked egg, complete with an acrid discharge and an angry prolapse. She laid another perfect egg today. So I am now on high alert for the next act.