
She could well be in her second fear stage, during which she'll be more likely to spook at things or be afraid of things she might not have been before. Best to back off for a bit, if she's doing fine with meeting strangers out and about then keep up with that but I'd hold off on having people go over her for a few weeks at least, maybe a few months. If you push it now and she's growling, she will just get worse. Practising handling her yourself by all means, pair it with fun stuff and perhaps have people she knows well do it but not on the table so she doesn't build a negative association with that spot.
The only calming thing I put any real stock in these days is melatonin, it is very good BUT better to just back off a bit and let her take things at her speed. At 5 months old, she shouldn't need any help like that and this is most likely part of her natural development. My collie pup became spooky as hell at about that age, but she's out the other side now and confident as ever :-)