"...please check out the info I provided earlier on the early exercise of PDL.TO..."

As I posted earlier, those warrants had an accelerated expiry clause from the beginning.

"...and I now also recall that Silver Wheaton also did the same thing a few years back on one of their warrant series that I use to own..."

I googled for that and found this 2008 news release. In that case there was no acceleration clause on the original warrants. But at a later date Silver Wheaton offered early expiry to the warrant holders. The offer was NOT binding on the warrant holders. As it says in the release... "any Existing Warrants that are not exercised during the Early Exercise Period will remain outstanding and continue to be governed by their current terms."