I just placed a buy order for 5,374 shares at the

I just placed a buy order for 5,374 shares at the ask which was .0335. It was filled immediately. However it shows an order filled for 10,748 shares, exactly twice the amount I bought and the ask was immediately raised to .0396. It appears a mm also bought 5,374 shares at the same time I bought mine- pretty odd. These mm's obviously use algorithms to trade electronically but I've never seen this happen before- a simultaneous trade for the exact number of shares I traded.