am i paranoid?

Thanks to the answers in advance :))

I realise an Algorithmic programme can react in a split second to manipulate a price once I confirm an order. But, can it detect the order being prepared,that is,before I confirm it. The other day it seemed that a sell order I did for ABU 'played me'- it was a steady sell price and the second I typed my price in the contract,it dropped. Was this just a strong coincidence?.

Some days these BOTS peeve you off ,but, the majority of the time I learn to trade side by side as best I can with excellent results. :))((: