That's what they get for sneaking around in the woods and not making their prescience known. I don't think you were at fault at all!
Agreed. I do suppose hwoever, if you tried sneaking up on the squirrel sheriff to make him [purposely] nervous by continuously pointing your "fake gun" at them, then maybe you'd be guilty of harrassing them .....
But if you were going about normal activities and using your handy-mounted spotter like it sounds ..... I'd remind the squirrel sheriff of a former Soviet (and still Rooshun) saying .....
"toughski [bleep]!" 
