There is and there is not. Verbs in Czech have many grammatical categories they follow. Gender, number (plural or singular), declension, pattern, etc. one of those categories is aspect. It defines if the action is finished or if it might continue. Most verbs exist in two versions, finished and unfinished.
Jít vs. chodit. Jít (to go) is a sample of a finished one. Once you get there you are done. Chodit (walk) is its unfinished counterpart. You walk to school every day.
Nést is an example of the finished verb. Once you get it there you are done carrying it. If you carried it every day, the verb is nosit.
In this sentence the verb is "nést" so once you get it there, you are done. Which means you must be carrying it right now. If i wanted to ask you what you carry thus suggesting it is a repeated action, I would say "Co to nosíš?"
Not all Czech verbs are this crystal clear. But in this case using present simple does not make sense.
Hope I did not confuse you too much.
Thanks. You have solve a big mystery for me. I saw several sentences like that where the English translation in present simple or present progressive was not accepted and I wondered what is the reason. Now I understand it's a way to convey the aspect. I'll try to keep it in mind from now on.