Shaft Extensions Coming Out

A few months ago I had the pro shop extend my "new" Callaway Steelhead x-14's i picked up on craigslist that were shortened 1/2 inch.  I got i think 1.5" extensions, possibly 2".  About 2 weeks ago, the extension in my 7 iron broke off in a normal routine swing.  Last week I noticed the extension in my 8 iron getting wiggley.  Today, the extension in my 5 iron broke off as well.

1. Is this normal?  If not, what is causing this.

2. Is there anything I can do to fix/prevent this at home?

3. I've heard I should get steel shafts, would it be better for me to get those in the correct length, or just keep repairing these?  Current shafts are Callaway Branded Graphites.

I checked the invoice, they were 1.5".  I'm not sure what type they are, but I took them to the pro shop but the man in charge of custom fitting clubs, regripping, extionsions, etc (not sure what that would be called, I have a limited golf vocabulary ) is out of town on vacation.  I talked to the head pro instead, who said this shouldn't be happening and that they would get a look at them as soon as everyone is back at work.  I'll keep updated as to what I find out.

Club technician.

Yes, thank you :)

I broke another off today and talked to him, and he just gave me a new set of clubs.  He said the joint between the extension and the shaft was nearly between my grip, and that I was too strong for  it.  The new clubs have steel shafts and if I like the clubs I'm going to get steel extensions in them.

So let me get this straight.... your clubs have graphite shafts in them? I must not have read the whole OP. 1.5" is alot for graphite. I've put as much as 2" extensions into steel, but would be hard pressed to do it to graphite. As a matter of fact I have a driver here that the previous owner put in a 1.5" extension and it's making noise.