Snoot booping during walks

My dog is very well behaved on a leash after some training, when we got her she was reactive towards cars, bikes etc but now it's just the occasional zoomies when she sees a bird and sometimes a couple of little excited barks when passing another dog. All and all a great walking companion.

However she has an adorable behaviour I don't really understand. It's mostly during long walks, towards the second half when she's gotten rid of some energy, that she starts walking very close to me and continuously booping my legs with her snoot. If I stop she just keeps pressing it into me over and over again and when I ask her what's up she stands on her hind legs and reaches for me almost like she's asking for uppies. If I keep walking she keeps snoot booping instead of focusing on her walk and sniffing the surroundings.

Normally I just pet and scratch her a little and tell her what a good girl she is before exclaiming "Let's go!" and keep walking but I wonder what she's really trying to tell me. She is young and has loads of energy, can play fetch for hours and we walk about 2-3 hours a day depending on the weather. We do some clicker training, play fetch and some easy scent work both indoors and outdoors. I can't imagine she's getting tired during our walks considering how much energy she still has, but I do feel like she's trying to connect with me and tell me something. Any theories of what?

We've had her just about three months now, she's a young rescue. Adapted incredibly well but there are still plenty of little things to learn about each other.