They don't forget, they're not trained to. With most "classical" vaccines it makes no difference. It's pretty well recorded. (There's been a podcast of one German expert on the topic, it's on youtube but it's in German obviously. He goes into detail on how myocarditis cases were seen more in patients that got the jab in a vax center, where mostly young recently-trained people worked, as opposed to resident GPs which tended to work the "old-school" way, with aspiration.)