What constitutes an OEM bulb? I think to be very sure, the bulb should be obtained from the manufacturer itself. As you read the previous threads, there seems to be lots of claims of companies offering OEM bulbs and having problems with them later on.
My working solution ultimately was to purchase the actual TY-LA1500 bulb package from Panasonic. Realize that Panasonic does not sell the bulb separately, but as a package including the bulb, enclosure, and a filter. And, it is expensive at $299 plus shipping costs, but I believe comes with a warranty. If you can find a company that is selling a truly unopened TY-LA1500 package (one without being refitted with another bulb), you can get it slightly cheaper.
It really seems bulbs are a gamble. When a bulb blows out, the companies will blame the ballast. When you repair the ballast, it seems you still have to replace the bulb because supposedly the ballast killed the original bulb. But, that replacement bulb soon dies also. Do you still blame the ballast, or the bulb? That is why companies restrict the number of replacements.
In your situation, it appears you have the same options as I did - either seek bulb replacement from Discount Merchant, or ask for a refund and apply that to a true Panasonic bulb. As I said, I got the refund, bought from Panasonic, and have had success since then ... it works reliably and consistently.
Please let us know of your decision, and of your ultimate success.