Spell Thief and Heimer Turrets

Hi there, I just played a game as a Support laning against a Heimer. I noticed that when you kill the one of his turrets your Spell Thiefs goes on CD.. what's this all about. Sure, I got 5gold from it however I missed out on more from my autos and spells against the Heim and the Graves. Is this an intentional thing or what? It's not the most game changing thing ever but I feel as though as the Support if you can get some free hits in on Heims turrets while hes Supporting, and possibly kill one of them while your AD is cs'ing or backing a little, my gold gen from Spell Thiefs shouldn't be hit. Soooo, slightly game changing from the Supporting role. I know when you fully upgrade it you no longer need to worry about losing the gold gen when killing minions but the early game against a Heimer and you're basically just forced to sit back and let the AD deal with the turrets.. I dunno. I also know Heim doesn't support too often either, thanks anywho who comments that, but still..

Comments please?

~Eternal