Fear @ 4: Is this a "normal" phase?

DS is still a fairly new 4yo, and I've noticed in the last few months he's really started having a lot more fearful episodes.  Some of them make total sense, like when he was up too late and caught a trailer on TV for a scary movie and freaked the heck out, but other times, he freaks out about stuff that doesn't seem scary at all.

Ex.1: We were watching Lilo & Stitch for the first time the other night, and he freaked out at a few scenes and started crying.  They weren't the high action, aliens shooting at Stitch scenes.  It was more like the scenes where Lilo was fighting with the other little girls or when she was yelling back and forth with her sister.

Ex.2: He was watching the hour long Bubble Guppies about fairy tales and freaked out about the scene with the witch.  I haven't seen it myself, but he was watching it with DH.  DH said that there wasn't anything scary about it, but he started crying and made him turn it off and delete it off of the DVR immediately.

Ex.3:  He saw some guy at the store, and for whatever reason, he was terrified of him.  The guy wasn't anywhere near us or even so much as looking at us, but DS couldn't be convinced that the guy wasn't going to hurt him/us.  We have never seen him before or since to my knowledge.

He's also started having a lot more bad dreams all of a sudden (kind of corresponding with the timeline of the previous examples).  I'm actually up now b/c he just woke up screaming b/c there was a "monster with pointy hands trying to punch [him]."

I feel like this must be some sort of normal phase, but it worries me a little.  Is this some sort of normal 4yo developmental phase or something to be concerned about? I'm wondering if it has to do with the development of his feelings or imagination somehow.  I just don't know though. 

The common thread (for the most part) is violence, and there is a kid in his class that is, shall we say, a problem.  He came home from school the other day saying that the other kid told him he was going to, "Kick the he!l out of [DS]," and then proceeded to kick him.  (FWIW, this has been addressed at school.)  I don't feel like this is necessarily directly tied into the fearful episodes, but again, I don't know what to think.

Thoughts?