Is A Bump Caused By Taking A Hit To The Head Harmful?

My seven year old son hit his head on a footboard of a bed at a friend's house today. He has a small laceration on the right side of his forehead near the hairline. He also has a large slightly black and blue raised bump around his temple area. He said he only felt pain in the area of the cut when he hit it, not in the area where he has the large bump. He did not lose consciousness, but cried after the hit. He has not shown any symptoms of concussion. He is asleep now for the evening. My biggest concern is the bump on his temple. It is large and the sight of it worries me. Again, his behavior is normal, and he only complains of pain if he touches it. I want to take him to the ER, but my husband thinks we should observe him and watch for worrisome symptoms. My question is, should I be concerned about that large bump. It has been six hours since he hit his head. Could it be serious even though he is not showing signs of concussion or brain injury?