Am I in the Wrong??

I had an incident that I was reported for at work. I am a new grad, 3rd week in and was left to my own devices last week with 4-5 patients on a post-op ward-my preceptor nowhere to be seen. So a patient came up from theatre, I checked his med chart, gave all required meds for the day and went home. Today (4 days later) I got called in for a discussion about how I have been reported (only me) for failure to give Aspirin. It was NOT charted when he came up, however was listed in a post-op info sheet that goes in the patients folder. It did not say when to give it/times etc. I understand I SHOULD have seen this and questioned it as to why it was not on the med chart…however it also means at least 5-6 nurses have also missed it that were looking after him during this time. Why am I the only one being reported?? Or am I missing something…should I do anything against it? I am just confused.

Thanks for your help!