Yes it's bad, but not maybe as bad as you may think. (You, yourself, obviously think it's bad enough to post your question in a relatively anonymous forum and in the "Addictions" category.)

Any kind of sleep medication can become habit forming, even if not physically addictive. Your body no longer responds to this the same way as it once did, as it your system has grown resistant to the relatively small dose of antihistamine found in Tylenol PM for its sedative properties. You have, perhaps, become mentally hooked on taking it. For those of us that have trouble falling asleep, bedtime can be a very stressful time, further preventing the relaxation needed before our minds will finally "let go". The very act of taking these pills each night may have, over time, become a necessary ritual that you equate with preparing for sleep.

I would seriously consider talking with someone about this, as it can become just as crippling as not being able to fall asleep, the very thing you sought to overcome through its use.

Best wishes.