My border collie who is now 22 weeks old still seems to be a bit timid although i must admit only at certain times

eg:strangers coming to house,new toys certain noises etc

Tonight while brushing my older collie with no problems i decided to brush kian afterwards he lunged for the brush but i think it was more in a scared sense than an aggressive one ,i proceed with treats and loads of praise but to no avail he ran behind the settee i thought if i backed down he would of won so i again tried by showing him that it was not going to hurt him by doing the older dog again in front of him,then i even lay the brush down beside him but he again snapped i have to add there was no growling though

Is this just normal puppy behaviour when scared of something new? my older collies 14 and i can never ever remeber him being like this

I carried on and gave loads praise and treats now i am here thinking is this going to be an aggressive dog or was i wrong the way i handled the whole situation ,any advice on this would be greatly appriciated
thanks