This sounds like a wash trade. Many times brokers will close your order and market makers close theirs. M&Ms will settle with each other with a wash trade, at end of the day to settle out their book. Basically I'm saying your trade could have closed Between M&M & broker or M&M and M&M on the first book level and not been reported electronically on the exchange until the transactions you notice.
There are 2 levels of order books on the OTC market. One between broker,broker/dealer,or market maker and on between market maker and market maker. The market maker transactions are reported, because they hold the share inventory which actually trades ahnds.
This system allows for arbitrage trading between all parties, except retail. This intra trading system allows for front trading. Where orders are close before your orders are closed and the brokers/dealers/M&M pocket the difference. To balance out all this activity sometimes trade are reported on the exchange which don't show actual transactions.