Without knowing the model number of your dryer I will not be able to provide any model specific information. If the high pitched whining noise was not there before you cleaned the lint filter and vent hose and you did not drop anything down the lint filter housing I will not be able to tell you what is causing the noise. If the vent system was severely restricted before and now is cleaned and blowing/moving more air could cause a different sound than when the vent was restricted. Some model dryers have a simple lint alarm device which works off airflow. If the vent is restricted it will make a high pitched tone.
Disconnect the vent hose from the back of the dryer and see if it still makes the same level and tone of noise.
NOTE: Reconnect the vent hose after making this test. Do not leave the vent hose disconnected
. If it quits making the noise with the vent hose disconnected would indicate most likely a restriction in the venting system.
Resubmit your question with the model number and any additional information for model specific information.