After almost a year of very up-and-down sleep (mostly down), ds had finally, FINALLY started sleeping pretty well. Last night he slept for around 13 hours without a peep, and he's been napping great for weeks now.
Today after his afternoon nap we accidentally left him after he woke up- baby monitor ran out of battery and we were in the garden. Not sure how long he was crying for but he was pretty upset when we went to him. Could have been ten mins or even longer 
Now this evening he just will not settle (has been dropping off instantly after a feed for.a while now, but not tonight). He cries whenever we leave room. Have been trying to settle him for an hour.
Could this be because of today's experience? He did also have around 16 hours sleep (!) in the last 24 so maybe it is that... But I'm scared we have broken him!
I feel horrendously guilty and also worried that we have now ruined his good sleep and given him a complex about being in his cot 
He is settling into childcare this week and I'm also worried this will make him clingy and affect that.
He is 11mo.
Someone please tell me I am reading too much into this... Or otherwise advise how to sort it out. Usually we would do controlled crying if he wasn't settling- but don't want to now in case he is traumatised!