Accidents at Pre School

My daughter is 4 in March. She goes to a pre school with 2,3 and 4 year olds twice a week. The staff at pre school don’t really talk to parents at handover, the children just come out the door and we leave. Anyway, today I’ve picked my daughter up and on the way home she mentioned that she wet herself whilst playing outside. I’ve obviously gone on to say oh no did so and so help you go and get changed.. and she’s told me that no one helped her and that she had to go into the toilets and get herself changed out of her wet clothes and changed again into fresh clothes from her bag by herself.. is this normal for in a pre school setting or should her key worker have helped? I know it messes up ratios having to dip in and out if kids have accidents but surely a couple of minutes to make sure she was cleaned up is better than leaving her to sort herself out? Just want to hear other peoples thoughts before I speak to them, thanks if you got this far!