I have two sets of molded ear plugs from two different vendors. One set I used last year. The other set has not been used much. I tried them both out this week. After maybe 15-30 minutes they start to feel pretty uncomfortable. Even painful after awhile. Both sets have the same discomfort, so I don't think it's a situation where they were made incorrectly. Is this just the nature of the beast? Do they, or my ears, have to go through a break-in period? TIA.