No, you shouldn't worry about this -- because God is more powerful than Satan, and even if the devil did try to block God's answer to our prayers, he wouldn't be able to do it. Remember, Jesus prayed openly, and He taught His disciples to pray openly (see Matthew 6:9-13).
In other words, our concern shouldn't be "Does Satan hear my prayers?" but "Does God hear my prayers?" Are my prayers selfish or greedy -- or am I honestly seeking God's will? Do I pray in faith, believing that Jesus Christ has opened the way for me to come into God's presence by His death on the cross -- or am I relying on my own goodness? Is any sin in my life blocking my fellowship with God? The Bible says, "The prayer of a righteous man is powerful and effective" (James 5:16).
It's been said that Satan likes us to believe either of two lies about him. The first lie is that Satan is weak and insignificant, and we shouldn't worry about him or be fearful of his schemes. The other lie says the opposite: Satan is all-powerful, and we are helpless against him.
In fact, Satan is not weak and insignificant; the Bible compares him to a roaring lion (see 1 Peter 5:8). But neither are we helpless against him -- if we belong to Christ. Make sure of your commitment to Jesus Christ -- and then remember: the closer you are to God, the further you are from the devil.